The present invention relates to method and apparatus for determination of nitrogen oxide. In particular this invention relates to method and apparatus for determination of nitrogen oxide in a high temperature gas stream.
Nitrogen oxides (NO.sub.x) are regulated by governmental agencies because they constitute a health risk. To satisfy these regulations, numerous processes for the removal or destruction of nitrogen oxides have been devised. Some processes utilize the reaction of nitrogen oxides with ammonia at elevated temperatures, either with a catalyst or without a catalyst. Under proper conditions, these reactants yield nitrogen and gaseous water nearly quantitatively.
Control of nitrogen oxide removal or destruction processes in an efficient, economical, and safe manner requires continuous monitoring of the concentrations of several species, including specifically nitric oxide, nitrogen dioxide, and ammonia, in the presence of nitrogen, oxygen, ammonium nitrate, nitric acid, and water, among other gaseous species. Conventional methods of analysis of these species, including chemical analysis of grab samples and instrumental on-line monitoring, are too time consuming and/or can only be performed at near room temperature. At such temperatures, deposition of ammonium nitrate can occur in transport lines or sample vessels, thereby causing low analytical results.
Accordingly, it is an object of the present invention to provide a method and apparatus for the determination of nitrogen oxide in a gas sample which yields analytical results having improved accuracy.
It is another object of the present invention to provide a method and apparatus for the determination of nitrogen oxide in a high temperature gas stream with improved accuracy.
These and other objects of the present invention, as well as the advantages thereof, will become more clear from the description which follows.